Telescopic, tubular plywood mast and method of making the same



1386- 1946- P. R. GOLDMAN TELESCOPIC, TUBULAR PLYWOOD MAST AND METHOD OFMAKING THE SAME 4 Sheets-Sheet 2 Filed Aug. 21, 1943 I nven 30?.- Pa/u/ZR. Go Eda-m alum :Hifys.

Dec. 17, 1946. h p. GQLDMAN 2,412,678

TELESCOPIC, TU BULAR PLYWOOD MAST AND METHOD OF MAKING THE SAME FiledAug. 21, 1945 4 Sheets-Sheet 3 ZEVIIIl/A. 40 mil/mIIIll/////////////////////////////[/ i 47 'l l I i i 177/7119 71/30 a":Pau/ZR. (Laura/an,

H- y BMM, Maw m 1946- P. R. GQLDMAN TELESCQPIC, TUBULAR PLYWOOD MAST ANDMETHOD OF MAKING THE SAME Filed Aug. 21, 1943 4 Sheets-Sheet 4 Invenfor: Paul R. Go Zdma/ZW,

at M, 411%,.

Patented Dec. 17, 1946 TELESCOPIC, TUBULAR PLYWOOD MAST AND METHOD OFMAKING THE SAME Paul R. Goldman, Andover, Masa, assignor to PlymoldCorporation, Lawrence, Mass.

Application August 21, 1943, Serial No. 499,573

4 Claims. 1

This invention relates to portable masts and mast assemblies particularlfor the support of radio antennae but adaptable to other purposes, andto their manufacture, packaging, transport and erection for use. It aimsto provide for such masts a sectional formation comprising separabletubular elements adapted for lengthwise assembly and also for nesting ortelescoping one into another, generally together with other tubularparts, to compact them into a transporting package of minimum length,cubic content and weight for amast of given height. Among the importantobjects of the invention is the adaptation of a wound and bonded woodVeneer or plywood construction to all main tubular elements of such mastand assembly, including not only the sections of the mast proper butalso certain accessory parts such as an incorporated erecting boom,holding means for the mast and the boom, and if desired a cross arm, allelongated elements save possibly for some of them in the exceedinglylong installations such as ninety feet or more being arranged forcompactly telescoping into a single unit package. Under the inventionother accessory elements preferably also are of plywood, and the entireunitary equipment is constructed and arranged for rapid and easyunpacking at the place of use, and for assembly and anchorage in asubstantiallyhorizontal assembling position of the mast proper whereinall points upon it are readily accessible, the mast then being easilymanually erectible to vertical use position by one person.

In order that the principle of my invention may be readily understood, Ihave in the accompanying drawings illustrated certain "embodimentsthereof, to which my invention is not limited, and which, thoughspecifically described, are intended as ex'emplary only.

In the drawings:

Fig. 1 is a somewhat diagrammatic representation, not to scale, of atypical mast assembly in erected or use position, in full line, apreparatory or assembling position being indicated in dotted line;

Fig. 2 is a plan view of the base assembly comprising a base plate andpivotally associated mast and boom cylinders or holders;

Fig. 2a shows one of the base plate pins;

Fig. 3 is a side elevation of the base assembly of Fig. 2;

Fig. 3a is a bottom end elevation of one member of the base assembly,namely the boom cylinder or holding socket;

Fig. 4 is a view mainly in vertical section on the line 4-4 of Fig. 3;

Fig. 5 illustrates in elevation a relatively short length of the typicalmultiple-ply wound and bonded wood veneer or plywood structure for theelongated tubular sections and elements such as the mast proper, theboom and any cross-arm, and also for the cylindrical holders;

Fig. 6 is a partly diagrammatic cross-section through a typical tubularplywood structure such as that of Fig. 5;

Fig. 7 is a diagrammatic lay-out of the tubular plywood sections for afive-piece mast, such for example as of fifty-foot or other length,including the boom and a cross-arm, such as in Fig. 1; V Fig. 8 is alongitudinal sectional view showing two next adjacent tubular woundplywood sections with the positioning ring, sleeve or collar secured inplace on the section of smaller diameter;

Fig. 9 is a longitudinal sectional view, on a somewhat larger scale, ofa portion of a tubular plywood section adjacent and including thepositioning ring, sleeve or collar;

Fig. 10 is a longitudinal section of the package or shipping unitcomprising the several nested or telescoped sections and elements;

Fig. 11 is a vertical cross-section of a cross-arm support which may beemployed at the top of the mast;

Fig. 12 is a vertical central section upon Fig. 11;

Fig. 13 is a horizontal section as on the line l3-l3 of Fig. 12;

Fig. 14 is a side elevation, partly in section, of the boom stay collar;

Fig. 15 is a top or outer end elevation of said collar of Fig. 14; r

Figs. 16 and 17 are respectively a side elevation and a plan view of amast stay collar; and

Fig. 18 is an elevational detail view showing a modified formof'securing means upon a tubular plywood element.

The structural character of a majority of the. tubular and hollowcylindrical elements of the mast assembly as a whole, being essentiallyinvolved in and largely contributing to the present invention, will nowbe described by way of introduction to a more detailed consideration ofthe component parts of the mast and accessory equipment and the methodsof forming, packaging and setting up the same for use.

For the purposes of such description reference is made to my copendingapplication Ser. No. 467,243, filed November 28, 1942, now Patent No.2,352,533, issued June 27, 1944, which I hereby preparing, winding andbonding together a mullayers or ply groups such as a, b and 0 each in Yturn made up of a plurality of windings or wrappings of thin wood veneersuch as c and c of Fig. 5, sometimes with one or more interposed thinmetallic or metal foil layers, all plastically bonded together underheat or pressure or both into a unitary tubular structure of lightweight and of great strength and rigidity both radially and axially.

As more fully described in said prior application, an inner or corestratum or ply-group a,

- Figs. 5 and 6, is formed by a plurality of relatively narrow elongatedveneer or plywood strips wound in edgewise abutment in an advancingcylindrical spiral or helix and with the individual wood pliesoppositely alternated in wind direction and having their grainpredominantly along the line of the spiral wind. The successive plywindings have between them a layer or coating of a suitable bonding andintegrating agent preferably of the thermosetting or polymerizable typesuch as an urea formaldehyde-or other plastic cementitious or adhesiveagent.

Around such plural-ply initial or core stratum a is formed alongitudinal strengthening and rigidifying stratum b, itself composed oftwo or more plywood or wood veneer plies applied as by straight-on orconvolute winding or otherwise so as to present the wood grainpredominantly lengthwise of the structure, that is, in generalparallelism with the tubing axis. These longitudinal applications aresimilarly interbonded with each other and to the core a as are theindividual plies of the latter. Over the resulting plural-strata bodya-b there desirably is furnished an outer or covering stratum 0, againpreferably composed of two or more windings of the veneer strippingwrapped spirally in alternately opposite directions. The resultingtubular or hollow cylindrical structure, the outer, inner and otherportions of which may be impregnated or otherwise treated to render themadditionally weatherand water-proof, is a substantially homogeneoustubing unit having hard and wearresistant surfaces and a high totalradial and axial rigidity inconsideration of its lightness in weight perunit of given size and length.

It will be understood that the described tubing is wholly or mainlynon-=metallic, save .in some instances for one or more thin or foil-likemetallic layers incorporated at any convenient position, for electronicor other purposes, as for example in another of my copendingapplications Serial No. 476,690, filed February 22, 1943, and that'it isfabricated in indeterminate lengths, of any required diameter, totalwall thickness and crosssectional shape, although generally cylindricalas illustrated.

Turning nowmore particularly to the mast assembly and equipment asfabricated from the described tubular plywood in further accordance withthe present invention, Fig. 1 shows somewhat diagrammatically anexemplary embodiment thereof, in. assembled and erected or use position.The several component parts or elements will first be generallyidentified and then described in more detail.

As here shown for illustrative purposes these comprise (1) a baseassembly, all of which, with exceptions to be noted, may be of plywoodincluding the flat or molded parts as well as the hollow cylindricalmembers; (2) the telescopic tubular plywood mast proper and itslike-formed erecting boom; (3) stay collars for the mast and the boom,those for the mast depending in number on the overall height or lengthof the particular mast; (4) a cross-arm assembly, which may be omittedin some types of masts; and (5) the packaging means or shipping caps forthe package or transporting unit generally comprising the nested ortelescoped mast and boom sections and the cross-arm when employed.

The general manner of assembly and erection of the mast equipment willreadily be understood by reference to Fig. 1. The base assembly thereindicated generally at H is set at any point selected for erection ofthe mast, with its base plate flat upon the ground or other supportingsurface and secured in position as by the indicated spikes (see Fig.2a).

Initially, for the purposes of assembly and erection, the mast cylinderor socket 19 of the base assembly is turned down into the'substantiallyhorizontal position as indicated in dotted lines at the lower right inFig. 1, the boom cylinder or socket 22 then being above the mastcylinder. The first or lowermost section A of the mast. of largestdiameter, has one end inserted into and secured in the mast cylinder.The several other tubular plywood sections of the mast such as B, C, Dand E are successively interfltted endwise by positioning of theirinserting ends into the receiving ends of the preceding section of nextlarger diameter. The erecting boom F is similarly fitted into itscylinder or socket on the base assembly, with its stay collar fittedupon its outer end. Any intermediate stay collar for the mast, such asindicated at 10 just above the mast section C in Fig. 1, is installed,as also the stay attaching means for the mast top in Fig. 1. Where themast is of the type including a crossarm assembly G, such top staycollarmay be incorporated with the cross-arm support 50, being so representedin Fig. 1, in other instances a top stay collar generally similar tothat for the boom being employed. These stay collars or the like areprovided with angularly spaced means for the attachment of stay wires orguy ropes as at the four quadrants of the mast, in the 12, 3, 6 and 9o'clock positions respectively.

Angularly corresponding anchor points are selected upon the ground.Three of these are indicated at X, Y and Z in Fig. 1, beingsubstantially equally radially spaced from the mast base, as about 20feet from it for a 50-foot mast, any suitable anchoring means beingemployed such as the eye-pins indicated in Fig. 1. It will be understoodthat as viewed in Fig.1 one such anchor point, as the point Z, isapproximately in line with and below the mast in its substantiallyhorizontal assembled but non-erected dotted-line position. The pair ofdiametrically opposed anchor points X and Y, each approximately frompoint Z, would actually in the position of Fig. 1 come substantially inline with the erected mast as there shown, but for the sake of clearnessin illustration, such anchorages X and. Y are shown set out slightly tothe right and left respectively. 1

At the fourth quadrant, substantially opposite the line of thenon-erected mast in its horizontal or flat dotted line position of Fig.1, a boom anchor point is provided as at W, preferably spaced radiallyaless distance from the base of the mast than the other anchorages, forexample 14 to' 15 feet or thereabouts in the case of the 50-footmastinstallation mentioned.

Before erection of the mast, its intermediate and upper stay-receivingmeans are connected by theindicated stays or guys of Fig. 1 with thecorresponding anchor points, substantially in the manner thereindicated. One such stayreceiver or eye of the boom stay collar 60 issimilarly stayed to the mast and its two next adjacent and mutuallyopposite eyes are stayed respectially as represented in the dottedlining of Fig. 1.

One person hauling upon the block-and-tackle may then easily and quicklyraise the mast to and secure it in its erected position of the fulllining of Fig. 1, as will readily be apparent from a consideration ofthat figure.

Base assembly.-Referring now more particu- I larly to Figs. 2 to 4, thebase assembly, referred to generally at Ii in Fig. 1, comprises the baseplate I: formed of a sheet of flat plywood having a series of holes l3through which securing means may be driven, such as spikes, one of whichis shown separately at H in Fig. 2a. Upon the base plate I2 is asupporting clevis, yoke or the like I5, also desirably formed of flat ormolded plywood and attached as by bolts or the like, the base platebeing formed with receiving bosses therefor if desired. While within theinvention this base plate and clevis may be formed otherwise than ofplywood, as of metal or other material, the plywood construction ispreferred in the interest of lightness. The spaced upright portions orarms of the clevis ii are horizontally apertured in alignment to receivea clevis pin or pivotal bearing it which may be provided with a metal orother bushing and with end washers I! together with means such as cotterpins i8 for I removably securing it in place.

Pivotally associated with the base-plate clevis through the medium ofthe pin it is a bracket indicated generally at 20, Fig. 3. It comprisesa lower or bearing portion 20a apertured for reception upon the pin l8and providing a seat as at 20b for the mast cylinder element l9. bracket20 may be formed of flat or molded plywood or otherwise, but in anyinstance the mast cylinder or socket element is preferably is made froma section of the tubular plywood material such as described inconnection with Figs. and 6, for direct reception of and contact withthe like-formed mast proper.

The bracket 20 further comprises a wing or lateral fin-likeextensionlllc having a bifurcated upper portion having bearing aperturesfor a pin 2| providing the pivot connection for the boom cylinder orsocket 22. This latter likewise is of the tubular plywood structure suchas that This of Figs. 5 and 6. Its pivoted inner or lower end hassecured to it a longitudinallyproiecting flange 22a received in theupper bracket portion 20c and apertured for passage of the pivot pin 2|,the latter provided with securing means as end washers and cotter pins,and if desired a bushing, in a generally similar manner as for thepivotal connection between the bracket 20 as a whole and the baseclevis'li. A crossmember 23 fixed adjacent the pivoted end. of the boomcylinder serves as a stop for the inserted end of the boom F. Thetubular plywood mast cylinder I9 is firmly secured upon thelower or seatportion 20b of the bracket and against the adjacent inner portion of thelateral extension 20c thereof, the bracket being of a general L- shapein side elevation and affording both horizontal and vertical support forthe mast cylinder in the upright or erected position of the mast inwhich the parts are illustrated in Figs. 2 to 4.

Appropriate means are provided for removably securing the mast and theboom in their respective cylinders l9 and 22 of the base assembly, onepreferred form of such means being shown in Figs. 2 to 4. For thispurpose the upper or outer portion of the tubular plywood walls of thesecylinders are each provided with a relatively narrow longitudinal recessor slot formation, as at liib and 22b respectively. These may be at anyconvenient point about the circumference of the respective cylinders andare of approximately one-half the longitudinal extent of the latter.Surrounding the slrtted upper end of the mast cylinder is a yieldableclamp element 24 of metal or other material, the upper portion 200 ofthe bracket 20 being recessed as at 20d to receive it. This clamp asshown comprises a split ring or collar having at its adjacent endsradially projecting ears 24a apertured to receive an adjusting screw,wing bolt or the like 25 threaded into a nut 25a. The latter may bewelded upon one of the ears, the threaded end of the bolt desirablybeing peened over to retain it upon the clamp. The slotted end of thetubular plywood cylinder 22' likewise is equipped with a resilient clampring 26 having similar nut and bolt tightening means 21.

Telescopic tubular plywood mast assembly- Referring now moreparticularly to Figs. 7 to 10, to be considered in connection with Figs.5 and 6 already described, I have in Fig. 7 diagrammatically illustrateda series of component tubular plywood elements A to E for a five-sectionmast, such as that of Fig. 1. Depending on the length and diameter ofthe individual sections the overall height or length of such mast may beselected within a wide rangebetween lowerand upper limits. Forconvenience in description. and merely by way of example, both Figs. 1and "I, also Fig. 10 may be regarded as representing a 50-foot radiomast, selected as typical of the invention. It will be understoodhowever that the mast of the present invention may comprise anyplurality of sections up to i nine or more, and may range in overalllengh from a few feet up to feet or more. In other words, a five-sectionmast may be other than 50 feet in total length, and conversely a 50-footor other length of mast may be made in other than five sections.

In the selected specific example of a five-section 50-foot mast thefirst and largest section A, for the lowermost position, mayappropriately have an outside diameter of 6 in. and a length of 10 ft.,6 in. The following sections such as 7 B to E graduate downward inoutside diameter, as for example 5, 4 and 4 in., likewise with overalllengths of ft., 6 in. for B to D sections and 11 ft., 9 in. for the topsection E.

The decreasing scale of outside diameter (0. D.) is continued as to theboom F which is approximately 3% to 3 in. O. D. and is illustrated as asingle-section element, an appropriate length for which in the assumedexample is not more than 11 ft., 9 in. The decreasing diametral scale isfurther continued as to the cross-arm G, if

such element is included. Such cross-arm G accordingly may be of 2 to 2%in. O. D., with a length of about 8 ft. more or less.

The relative lengths and diameters of the 4 tubular plywood sections orelements A to G are by the invention calculated with particular view tothe desired nesting or telescoping of the entire mast assembly into apackage of minimum bulk, such as illustrated in Fig. 10. The exemplarysection lengths given above are overall. That is, as to the intermediateand top mast sections 3 to E they include the joint-forming orrelatively short inserting portions and also the relatively longerexposed portions, the latter in turn including, in the illustratedexample, the external abutment or positioning collars 40 to bedescribed. Such inserting portion for the sections B, C and D, in theexample under consideration, may be 12 in. and for the top section E, 9in., said collars having a length of 3 in. or thereabouts. This resultsin the assembled position of Figs. 1 and '7 in the selected total 50-foot length for the mast, made up of the 10 ft., 6 in. extent of sectionA, the exposed extents of 9 ft., '6 in. each (including their collars)for sections B, C and D and an exposed extent of 11 ft. for the topsection E (including its collar).

To give but one other dimensional example the several hollow tubularelements for a 90-foot mast assembly elected to comprise nine sectionsfor the mast proper (the number may be other than nine) the O. D. valuesmay be 7 /2, '7, 6 6, 5 5, 4 /2, 4 and 3 in. respectively, withindividual lengths of 10 ft., 9 in. (overall) and 12 in. inserting orjoint portions, the final or topmost section being somewhat longer ifdesired. A twosection boom of about 20 ft., 6 in. assembled length maythen be provided in such instance, one section of 10 ft., 9 in. and theother of 9 ft., 9 in. plus a 12 in. inserting or joint portion Thecross-arm if any may be any desired proportionate length, as 9 to 11it., such plural-section boom and cmss-arm being diametrallyproportioned for nesting with the mast sections or for mutual nestingseparately therefrom. In any instance it will be understood that thewall thickness of the sections is not greater than, and for tolerancepurposes preferably somewhat less than, the 0. D. difference betweensuccessive sections.

By way of emphasis, it is again noted that the invention, whilecomprising the relative proportioning, arrangement and structuralinterrelation of the several tubular elements is in nowise limited tospecific dimensions of parts, such considerations as length, outer andinner diameter, wall thickness and others being determined in accordancewith the circumstances and demands pertinent to the particularinstallation and attendant use conditions.

Among the important features of my present invention, both as regardsthe mechanical structure and the method of fabrication and assembly, arethe abutment or positioning elements,

rings or collars 40 briefly mentioned above, for

accurately relatively locating and supporting the assembled mastsections. One such element It is incorporated with each mast sectionexcepting the largest or lowermost section such as A. These tubular orcylindrical elements 40, similarly as the tubular mast sectionsthemselves, preferably are constructed of wound wood veneer or plywoodin the manner as explained in connection with Figs. 5 and 6, but withinthe invention may be otherwise formed. Further, it is of substantialimportance that such positioning or abutment element for any givensection shall conform dimensionally with the section to be engaged by itand that its abutting end wall shall have a firm and direct seat-againstthe corresponding end wall 01' such engaged section.

Noting particularly Figs. 8 and 9, each such abutment element comprises.a ring, sleeve or collar 40 preferably, as stated, of multiple-plywound tubular veneer or plywood formation described. ;Since such element40 for each section so equipped is or may be similar except as todiameter, the reference numeral 40 is applied generally in Fig. '7 oneach of sections B to E. Figs. 8 and 9, illustrating the preferredconstruction in more detail, may be regarded as representative of any ofsuch sections B to E. Further, these butt-joint defining elements 40 maywithin the invention be disposed either inter-' nally or externally ofthe' respective sections. When internally disposed they may be locatedadjacent the upper or outer ends of successive elements beginning withthe lowermost or largest, such as A, thus requiring none for the last ortop section such as E, or they may then be in the preferred relativepositions as indicated in Fig. 7 for their external locations. As thefabricating method and means of securing these abutment rings, collarsor the like 40 may be substantially the same whether inside or outsidethe tubular plywood mast sections, it is suflicient to illustrate themas external, which construction is preferred as generally facilitatingthe manufacture, inspection and use of the parts concerned.

As one feature of the structure and method of the invention, theseabutment elements, rings or collars 40 are preferably not only of themultiple-ply wound tubular veneer or plywood construction of Figs. 5 and6., but also are directly out or otherwise taken from-a portion of thesame or a similar tubular plywood element which is to be employed in theformation of the mast section of next larger diameter (or smallerdiameter in the internal form) than that to which the panticular ring orcollar 40 is to be secured.

Desirably such collar piece is so utilized that in the assembly ofagiven mast-it ,will abut endwise against the plywood tubing portionfrom which it was cut oil", and in substantially thesame circumferentialrelation, thus insuring accurate counter-fitting abutment between thesubsequenstly assembled sections. It is to be understood, however, thatwithin the invention the collar elements 40 may be made separately orotherwise than as above described; but for speed and convenience theyare fashioned from a wound tubular plywood section of the appropriatediameter.

It is of the utmost importance that these rings, sleeves or collars 40be secured firmly and accurately on the tubular plywood sections towhich they pertain. Noting particularly Fig. 9, for that purpose Idesirably first apply a layeror coating 'eral engaging sections.

of an adhesive or bonding agent 4|, such for exampleas in the tubingstructure of Figs, 5 and 6, to the appropriate surface area of theparticular plywood tubing section. I overlay the adhesive with one ormore turns of thin wood veneer as indicated at 42, as a. filler andseating means, to a total thickness substantially equal to the diametraltolerance factor as between the section to which the collar is beingsecured and that with which said section is to be interfitted. Anotherlayer or coating of adhesive desirably then is applied as at 43. Then Iplace the ring, sleeve or collar 40 itself concentrically in position intransverse line with said means 4| to 43, its accurate axial parallelismwith the tubing axis being assured by said means, and also the trueperpendicular relation of its end walls or edges relative to said axis.One or more screws 44 or equivalent mechanical connector means are thenpassed through the collar and into the substance of the tubular plywoodsection itself. Deslrably as stated I combine the securing means 4| to44, but in some cases any one of them might be omitted. However, it isconsidered important to employ at least two of these elements or means,namely the adhesive or bonding agent, the veneer winding and themechanical connector, and preferably all three.

In order readily to nest or telescope the tubular plywood elements ofthe mast assembly into a unitary package for shipping, as illustratedfor example in Fig. 10, a substantial tolerance is provided as betweenthe outside diameter of a given section and the inside diameter of theone next larger and into which the first is to be telescoped. At thesame time it is of extreme importance that the inserting portions of therespective mast sections, that is, their portions between the abutmentcollar 40 and the nearer end of the given section, shall have a firm,tight fit into the cooperating section, in the assembled position of themast as in Fig. 1. Such tight interfltting however must be consistentwith the desired capacity for rapid dismantling and repacking of themast.

Accordingly, and referring now particularly to Fig. 8, I apply about theinserting portion of the typical mast section such as D to E thereillustrated, one or more turns or winds, preferably straight-on orconvolute, of thin wood veneer 45. This may have a gauge of the order of/64 in. more or less, and is applied to a total thickness approximatingor somewhat less than the described dimensional tolerance between thesev- Such additional veneer layer or layers are bonded into position,desirably similarly as in connection with Figs. 5 and 6. They are thenworked down as by sanding or other shaping and finishing operation toafford them a definite but scarcely noticeable l0ngitudi-- nal taper, asat I46, Fig. 8. Said tighter layer 45 and the associated taper formation46 desirably are extended along a major length of the inserting portion,substantially as represented in Fig. 8, from the abutment collar 40 tocrapproaching the adjacent end of the given section. It will beunderstood that in a construction wherein the abutment elements orcollars 40 are internally located, this tightener or taper element 45-46is correspondingly internally applied.

By reference now more specially to Fig. 10, illustrating a nested,telescoped or packaged condition of the elongated tubular elements of afive-part mast assembly, together with the boom F and cross-arm G ascomprised in the typical equipment of Figs. 1 and 7, it will be observedthat the sections A to E are disposed one within atively longer portionof the given intermediate section (B), that which is exposed in theerected Fig. 1 position, is received within the next larger section (A),up to the collar 40 of the received section, .The relatively shorter orinserting portion of the received section, that at the left in Fig. 8,and which here externally carries the described taper fitting formation45-48, accordingly is not directly engaged circumferentially by anyenclosing part, In this manner the tightfitting feature for theinserting portions of the several mast sections is coordinated with thefeature of their telescopic nesting and packaging for transport.

It will further be noted in this connection that the relative lengths ofthe several tubular plywood elements of the entire assembly are socalculated as to afford the desired compact minimum-length package, suchas that of Fig. 10. The latter represents a five-piece mast structuretogether with the appropriate boom F and a cross-arm G, as assumed inthe typical embodiments of Figs. 1 and 7, already described by way ofone specific dimensional example as a 50-foot installation. Againreferring to the stated exemplary dimensions for a mast of said 50-footheight, it will be seen that the overall length of the package is but 11ft;, 9 in., as determined by the longest of the several sections, inthis. instance the top mast section E, seen in the fifth from outermostposition in Fig. 10.

For the assumed 50-foot mast an appropriate length for the erecting boomF likewise is 11 ft., 9 in. As previously stated, it is diametrallyproportioned with reference to the top mast section E. Accordingly it isadapted both diametrally and longitudinally for telescoping as asingle-section unit within such mast section (E), and is so shown inFig. 10. V

A single-section cross-arm such as G up to a length of as much as 11ft., 9 in. may be provided consistently with the formation of thedesired minimum-length telescoped package such as that of Fi 10. Suchcross-arm G, when employed, desirably is diametrally graduated in thesimilar descending scale, as previously stated, thus adapting it forreception within the boom F, where it is shown in Fig. 10. Since anappropriate cross-arm length for the 50-foot mast assembly of theassumed example is but 8 ft. or thereabouts, such cross-arm element G asrepresented in Fig. 10 is substantially shorter than the boom section Fin which it is received.

Further in connection with the package of Fig. 10, and considering stillthe assumed example of a 50-foot mast made in five sections with theillustrative dimensions as already listed, it will be noted that theoverall length of any two successive nested intermediate sections suchas B and C likewise totals 11 ft., 9' in. That length is comprised bythe two mutually nesting longer portions. or such sections, occupyi alength of but 9 ft., 3 in. (9 ft. 6 in. less the 3 in. extent of theircollars 40) plus the combined 6-in. length of their respective collars.plus the combined 2-117- length of their respective shorter or insertisuccessive nested sections lie at the opposite ends 7 of the packagesuch as that of Fig. 10. It will be noted in that figure as to the fifthand in this instance top mast section E, having a somewhat shorterinserting portion (9 in.), that its abut ment collar 40 islongitudinally spaced from the adjacent end of the next larger section(D) and out of transverse line with the collar of the second-largersection (C). Thus within the invention, and with reference both to thestructure and assembling of the mast and to the telescopic packaging ofthe tubular elements, a substantial opportunity for dimensionalmodification is afforded.

In order to hold the several tubular plywood members orsections in theirnested or package position of Fig. 10, I provide packaging means hereinconsisting of-shipping caps 41, 48 for the respective ends of thetelescoped sections. Each consists of a cylindrical or laterallyenclosing part 41a, 48a respectively, those desirably of the' woundmulti-ply wood, veneer or plywood structure of Figs. and 6, and havingsecured at their respective outer ends transverse strips, crossmembersor heads 4'"), 481), preferably of a fiat plywood formation. Suchshipping caps are of like diameter, to fit snugly over the outermost ofthe nested sections, here section A. They have a length or depthadequate for substantial lapped or elements generally constitute thedesired compact minimum-length package for transport. In mast types nothaving cross-arms, the latter is omitted from the package, while in anyof the 'masts of extreme height, such as in excess of 70 to 80 ft. orthereabouts and which may require a plural-section boom, such boomsections are themselves proportioned for telescoping reception in thepackage unit, or they may form a separate package, together with thecross-arm if any.

It will be evident from the foregoing descrip-.

tion that my invention includes that method of making a telescopictubular plywood radio or like mast which involves first the step ofconstructing a series of multiple-ply tubular wound veneer or plywoodsections of successively lesser diameter and each incorporating bothspirally wound veneer layers or plies and also an intermediatestraight-on or convolut wound length-grained multi-ply veneer stratumall unitarily bonded together; severing from such or similar tubularplywood sections a corresponding series of rings or tiple-ply tubularveneer material of each ring or collaris in assembling the mast broughtinto an edge-to-edge relation with an end edge of the next section, andaround the full circumference of the engaged parts, thus providing anaccurately abutted joint structure, wherein like materials are mutuallyinterengaged. Hence an end wall of one mast section and the opposed endwall or edge of the adjoined ring or collar of the next directly engageeachv other in a symmetrical arrangement or continuation one of theother, so as most effectively'to support the weight of the sectionsthereabove. Each ring or collar acts as a limiting or positioning devicefor each adjoining pair of tubular plywood sections. That is, in theexternal form illustrated, each collar abuts directly against the upperedge of the section next below it, preventing further relative endwisemovement between them and directly transferring the weight of thoseabove to those below. In such case the lowermost and as hereinillustrated the largest of the sections, bearing the greatest weight,has no collar and is engaged directly upon its upper end wall or edge.

If the rings or collars are positioned internally instead of externally,it will be understood that each mast sec-tion except the topmost, butthen including the lowest section, has such a ring or collar securedtherein, whether the several sections are of graduated diameter orotherwise. In the preferred construction the mast sections are ofsuccessively smaller diametenas herein shown, the abutment means orcollars 4 0 are external and the largest mast section (that is, the Ilowest when the mast is assembled) omits such ring or collar.

The cross-arm assembly-"This element of' the mast equipment willbeunderstood as optional. Installations which do not require a cross-armhave substituted therein a m'ast top-stay collar such as subsequentlydescribed in more detail herein with reference to the mast-erecting boomand by reference to Figs. 14 and 15. When employed, the cross-armassembly includes a support or fitting unitshown particularly in Figs.11, 12 and 13 and there indicated generally by the numeral 50. It may beof metal or of other construction, such as the wound multi-ply veneertubing formation of Figs. 5 and 6, in which case the stay-attaching eyesand the securing means to be referred to are attached as by screws,rivets or the like, or by welding or other attachment to securingmembers or strips as in Fig. 18 to be described.

Said fitting or unit 50 mainly comprises two cylindrical members ortubes 5|, 52 disposed and vided at the upper end of member 5|. The loweror upright tube 5| of this unit, having reference to its use position,is adapted for seated reception on the free end of the final or top mastsection,"such as E of Figs. 1, 7 and 10. There is provided at its outerwall, as by welding, a number of rings, eyes or the like 53-corresponding in number to and similarly angularly spaced as the mastand boom anchor points, such asW, X, Y, Z, previously referred to inconnection with Fig. 1. These eye formations 53 receive the stays, guywires, ropes or chains leading to three of the anchor points as X, Y andZ and to the outer end, this cap-like tube is provided internally withlimiting or seating means for engagement with the top or outer end wallof the last mast section (E). As illustrated such means comprises aninturned annular rib or flange 54, integrally or otherwise formed.Between such means 54 and the horizontal tube member 52, the member 5|may be tapered or flared, depending on the relative diameters of the twoperpendicularly related tubular parts 5|, 52, such taper formation beingindicated at 55, Figs. 11 and 12, as appropriate for a cross-arm G ofsmaller diameter than the top mast section such as E.

The top or horizontal tubing member 52 (again with reference to the useposition) forms the immediate receiver or holder for the cross-armproper, such as the woundtubular plywood element G referred to atvarious previous points in connection with the consideration of Figs. 1to 10. This tubular element G, generally constituted as a one-piece orsingle-section tubing unit is, in

' assembling the parts, inserted through said member 52 of the cross-armsupport to the proper distance, usually so as to extend equally atopposite ends thereof, and is removably fixed in place. For this purposethe holder member 52 is provided with one or more apertures through itswall, the tube having welded or otherwise fixed at its outer surfaceopposite each such aperture a nut 55, one of which is indicated at theupper central location in Figs. 11 and 12, receiving a thumb screw, wingbolt or the like 51 for securing engagement with the installed crossarmG. The mast-engaging or upright tubular member 51 of the support unitdesirably also is equipped with securing means. As seen at the lowerright in Figs. 12 and 13, such means comprises a welded nut 58 andassociated wing bolt or thumb screw 59 similarly as for the cross-armreceiving tube 52.

The described support or fitting unit 50 of Figs. 11 to 13 thusconjointly incorporates in effect a top cap for the mast, a mountingmeans for the cross-arm and also a receiving collar or attaching meansfor stays or the like at the mast top. The unit as such presents a novelstructure constituting a feature or sub-combinational element of theinvention as a whole. As noted, for mast installations not requiring across-arm, a top stay collar is provided for the upper mast section.Such collar may consist of a tubular element substantially similar tothe lower or upright tube 51 of the described support unit 50, up to andincluding the transverse fitting means or flange 54 thereof, being thengenerally similar to the boom stay collar now to be described, except asto one of the stay-attaching eyes.

The boom stay coZZar.-The erecting boom for the mast, such as the woundtubular plywood element F previously mentioned, and which may consist ofa single section as illustrated or a plurality of interfitted sectionssimilarly constructed and adapted for telescoping as the described mastsections such as A to E, has provided for its outer end a collar or likedevice for attaching reception of one end of certain of the mast stays,two of the anchor stays or chains, and one end of the block-and-tackleequipment, all as previously described in connection with Fig.1. In mastassemblies up to and including those of 70 ft. or thereabouts suchsingle-section boom may be employed.

Referring now more particularly to Figs. 14

and indicated as a whole by the numeral 80,

comprises a ring, sleeve or the like 8| having welded or otherwisesecured at the appropriate points about its outer wall a plurality ofrings, eyes or the like. Three of these, as indicated at 62 project inplanes radial of the collar proper 6|. A fourth eye 53 of such pluralitypreferably is disposed at right angles to the others, in a planetransversely perpendicular to the collar axis. This latter eye 53 isthus better adapted for the attachment of the block-and-tackle of Fig.1, while the other eyes 82 as disposed are appropriately presented toreceive the corresponding mast and anchor stays or chains as alreadyexplained.

For properly locating and seating the boom stay unit 60 at the outer endof the boom such as F and positively to prevent its undesirably ridingdown upon the boom, it is provided with means such as the inturnedflange, annular rib or the like 64, adapted for seating engagementagainst the outer end edge or wall of the boom. As in the instance ofthe member 5| of the cross-arm support of Figs. 11 to 13 such locatingand limiting means 64, which need not be circumferentialiy continuous,may be integrally or otherwise formed, as by inturning one edge portionof the wall member 51. Such flange or like means 54 desirably conformsin width to the wall-thickness of the tubular section with which itengages, particularly when the particular end collar is to be employedat the top of a mast not having a cross-arm as above referred to. Anopening giving access to the hollow interior of the: mast is thusafforded as may be desired for the installation of electricalconductors, wires or other means. A welded or otherwise amxed nut 65 andassociated thumb screw or wing bolt 66 desirably is provided forremovably securing the boom stay collar in place, similarly as inconnection with the cross-arm support 50.

Intermediate mast stay collar or collars-With many installations,particularly the relatively shorter masts up to 40 feet or thereabouts,no staying generally is required other than at the mast top. In otherinstances one or more sets of intermediate stays are desirable and forthe purpose of the present disclosure I have assumed such to be the caseas to the five-section mast illustrated, whether the same be of theassumed 50-foot length or otherwise. One such stay attaching means isillustrated by way of example in Figs. 16 and 17, the unit being thereingenerally indicated by the numeral 10. In the typical assembly of thefive-section mast such stay unit or collar may appropriately be disposedjust above the third mast section, such as section C of Figs. 1, 7 and10, being so indicated in Fig. 1. In for example seven to nine sectionmasts, stay collars generally are located just above the fifth sectionand the seventh section. I

Each such collar consists of a metal or other ring 11 of the properdiameter for reception at the desired point of the given mastinstallation. This ring has welded in radially projecting positionaboutits outer surfacela number of stayattaching eyes or the like 12,four being represented in this instance, equally angularly spaced. Inthis connection, and also with reference to the stay-attaching means ofFigs. 11 to 13 and Figs. 14 to 15, the-eyes or like members may be otherthan four in number and otherwise spaced and 15, illustrating apreferred construction for than as herein represented. The illustratednum- 15 ber of four, however, is preferred as most convenient andefllcient for the purposes. 7

In Fig. 18 I have illustrated an alternative form of clamping orsecuring means such as may be employed in association with any of thehollow cylindrical multi-ply wound veneer or plywood elements withinwhich a received member is to be releasably fixed. Such elements mayinclude for example the mast cylinder IQ of the base assembly. the boomcylinder 22 thereof and one or both tubes 52 of the cross-arm support.With reference to said mast and boom cylinders l9 and 22 the means ofFig. 18 represents one alternative structure in place of the clamp-ringand slotted-cylinder formation described in connection with Figs. 2 to4. The multi-ply wound veneer or plywood tubing S of Fig. 18 accordinglymay be regarded as representing a section of any of the cylinders ortubes above mentioned. A short steel or other metalstrip 80 arcuatelyshaped at its inner face to conform to the tubing surface is secured tosuch tubing S as by wood screws, rivets or the like 8|. At an aperturein the strip, and which is continued through the adjacent wall of thetubing S, there is fixed at the outer face of the strip '80, preferablyby welding, a nut 82, for reception of a wing bolt, thumb screw or likethreaded member to be set up against or into the inner element to besecured.-

Any desired plurality of such nuts and threaded members may be employedon a given strip, and a plurality of the latter may be variously locatedon any given tubular plywood section.

Having now described the readily portable mast assembly of the inventionand the method of proportioned structure, arrangement and fabrication ofits component elements, their packaging for shipment and theirassembling and erection for use, it will be understood that theinvention, while especially adapted to the field of radio masts, forwhich purpose it now includes among other users the armed forces of theUnited States, is applicable to numerous other uses, as for one example,in tent poles of various types and sizes, indeed for any work wheretelescoping tubular structures having the warmth, lightness and otherbeneficial characteristics of wood are advantageous. As explained, theoverall or assembled length of my telescopic tubular plywoodstructurehas a potential wide range. By way of further example, it maybe as short as a 3-foot tent pole comprising14 in. sections, or it maybe a 90-foot or longer mast, having any convenient number of sections upto nine or more. It also will be apparent that the multiple-ply woundwood veneer or plywood formation as described in connection with Figs. 5and 6 and by reference to my earlier applications identified largelycontributes to the practical success of the invention, especially byreason of the incorporating of the longitudinally rigidifying layers,plies or strata thereof in which the grain of the wood is predominantlyparallel to the axis of the tube sections.

While I am aware that telescoping tubular devices of metal are known,and that non-telescoping or nesting poles involving plywood have beensuggested, I believe myself to be the first to provide a telescopingtubular mast embodying interfltting and nestable sections of woundmultiply wood veneer having the advantageous features of greatstrength,/ lightness, compactness, warmth and the others as and for thepurposes as herein disclosed.

Further by way of example in this connection,

the required shipping space for a 50-foot mast embodying my invention,of the structure and arrangement as above described with reference toFigs. 1, 7, 10 and the others, is but 2.43 cubic feet, as'contrastedwith 9 cu. ft. or more for a sectional but non-telescoping ornon-nesting wood mast of like height, and even greater cubage for atelescoping metal structure of said height, due to the bulky equipmentrequired by reason of the great weight of such metal device which.totals 400 lbs. or more as against but about 125 lbs. for I a 50-footmast assembly of my invention. Moreover, my mast, such as that of saidexample just noted, may be completely unpacked, assembled and erected byone person within about 30 minutes. Any at all comparable installationhas heretofore required a crew of five men working three hours and inaddition the use of a marine winch for the erecting of the metallic typeof mast of a height of the order mentioned.

In the-preferred embodiment all or substantially all of the parts andelements of my assembly are or may be of the tubular wound plywoodstructure disclosed, as to the cylindrical members, or of a flat orformed plywood as to noncylindrical members, with the exceptions of thefittings, collars, bushings, pins and the like as noted. It will beevident from the foregoing, however, that metal may be employed forcertain of the subsidiary parts other than those of said exceptions,such for instance as the base plate, the clevis Or other parts of thebase assembly. Also it will be understood that the split tubularformation and associated annular clamping means as illustrated anddescribed in connection with the cylinders for the mast and the boom mayalso be utilized at other appropriate points as for the fixing of theboom stay collar, the mast top-stay collar for the non-cross-arm typeand the cross-arm supporting means of the type so equipped.

Having thus described certain embodiments of the invention and the bestmode known to me for practicing the methods thereof, it is to beunderstood that although specific terms are employed, they are used in ageneric and descriptive sense and not for purposes of limitation, thescope of the invention being set forth in the following claims.

I claim:

1. That method of making portable tubular sectional telescoping radiomasts which comprises fabricating lengths of cylindrical tubing ofdiffering diameter by spirally winding and convolutely layingconcentrically a multiplicity of plies of wood veneer to a given wallthickness and interbonding them into substantially homogeneous tubingstructures, forming therefrom a series of cylindrical tubular mastsections of generally similar length and graduated in outside diameterby differentials slightly exceeding their respective wall thicknesswhereby to adapt them for endwise interfitted extended assembly and alsofor an endwise reverse telescopic packaging one in another, severing arelatively short annular portion from one end of each tubing lengthexcept the smallest thereof, wrapping and ad hesively securingexternally about the inserting end portion of each of the smaller tubinglengths wood veneer to a thickness substantially equalling thedifferential between its outside diameter and the inside diameter of thenext larger tubing thereof the annular portion severed from the auaevs17 next larger tubing and there firmly securing it adhesively andmechanically and reducing the veneer wrapping circumterentially betweenthe installed annular portion and the adjacent end or the tubing along agradual and substantially uniform taper outward over a major extent ofits inserting end a concentric plywood tubing collar for direct endwiseabuttive engagement with the end wall at the receiving end of the nextlarger section, said sections having a differential between the outerdiameter of one and the inner diameter of the next larger adapting themfor reverse telescoping in on another, said collars for the respectivesections comprising relatively short lengths of the plywod tubing forthe next larger section and each having concentrically disposed betweenit and its fixedly carrying section plywood filler and adhesive bondingmeans equalling in thickness said diametral diflerential.

3. In a portable sectional mast for communications. a plurality ofelongated plywood tubing sections of approximately equal wall thickness,each of uniform diameter, the outer diameter of one being less than theinner diameter of the next by a differential adapting them foroverlapping endwise interiltting in assembled position and for endwisereverse nesting, and means carried by one section for positivelylimiting the extent of assembled overlapping interilt and fortransmitting end thrust by direct engagement with the adjacent end wallof the next section in a transverse plane perpendicular to thelongitudinal axis of the sections, said means comprising a plywod tubingring concentrically disposed on the carrier section in predeterminedspaced relation to the interfltting end thereof, of an outer and innerdiameter conformant to the next section and having an outer end wallperpendicular to the section axes, a plywood layer interposedconcentrically between the tubing ring and its carrier section andbonded at opposite circumferential faces to the ring and the carriersection respectively, said layer and bonding equal in thickness to thediametralldiflerential between the sections, and mechanical meanstransversely interconnecting the plywood tubing ring, the plywood layerand the carrier section.

4. In a portable sectional mast according to claim 3, a constructionwherein the plywood layer associated with the plywood ring is extendedfrom the latter substantially to the adjacent end of the carrier sectionand is gradually tapered conically from a maximum thickness at the ringtoward a zero thickness at said carrier section end. 1

PAUL R. GOLDMAN.

